Kinda what it says in the title!
A little guide for the eye....
density diamond ~3.5g/cm3
density mercury ~14g/ cm3
How high it floats is actually partially a combination of surface tension and density. Nonetheless the inverse ice cube look is quite cool!
I wont be adding this video to the patreon supported feed, but if you like this video and want to support more like it:
/ thunderf00t